SARS-CoV

SARS-CoV is the coronavirus (CoV) that causes severe acute respiratory syndrome (SARS). CoVs are enveloped viruses with a positive-sense, single-stranded RNA and can cause health-threatening outbreaks by targeting human respiratory system, including not only SARS, but also Middle East respiratory syndrome (MERS) and SARS-CoV-2 (the cause of COVID-19).

CoVs have four main structural proteins: spike(S), membrane (M), envelope (E), and nucleocapsid (N) proteins. An S protein mediates the CoV entry into host cells by attaching to a cellular receptor (ACE2 for SARS-CoV and SARS-CoV-2, DPP4 for MERS-CoV), followed by fusion between virus and host cell membranes. Genome replication and subgenomic RNA transcription after entry carry on with the participation of many nonstructural proteins such as Mpro (main protease or 3CLpro), PLpro (papain-like protease) and RdRp (RNA-dependent RNA polymerase). Then the structural proteins are translated, assembled into mature virions, and released via vesicles by exocytosis. It is worth mentioning that a protease called TMPRSS2 (transmembrane protease, serine 2) play important roles throughout the whole life of CoVs (such as attachment, assembling and release) by cleaving S protein. All the proteins and subcellular structures participated in the life cycle of CoVs are promising targets for treatment of disease caused by CoVs.